SDN networks arose from a demand for connectivity that current switches, routers, network protocols and segmentation tools could not satisfy.
Cloud-ready data centers enable an always-on and available-anywhere world of information and productivity. The cloud computing model delivers efficiency and value with economies of scale by pooling compute, storage and networking resources, distributing them where they are most needed, maximizing their use across multiple groups and abstracting away the underlying physical infrastructure.
Some of the biggest inefficiencies and costs of traditional networks arise from tedious, manual configuration and management, performance bottlenecks, connectivity and bandwidth costs, lack of service agility and threats to security. To fully realize the benefits offered by cloud computing, IT teams must overcome networking challenges with virtualization.
SDN networks to the rescue
Much like servers, network infrastructure can be virtualized so that workloads and data sets dynamically and automatically move between the distributed and heterogeneous cloud server and storage pools. This set of technologies is collectively called software-defined networking (SDN).
SDN networks make use of an unprecedented level of programmability, allowing application services to tap into control plane abstractions of network data flows in real time. This enables automated instantiation programming and control -- custom data flows directly between application services, between applications and their data sources and datasets, and between applications and their end users.
A software virtual switch circumvents the basic limitation in physical switches for network segmentation and connectivity, using virtual local area networks. The virtual switch demonstrates the importance of a logical separation of the control and management planes from the forwarding plane. This separation, empowered by standardized protocols and application program interfaces, is the cornerstone of virtualizing a network.
The most obvious advantage of an SDN data center network is its promise of simplified network management. SDN-style orchestration makes it easier to implement policies required to segment data center networks by traffic type, service-level agreement, time of day, etc. Orchestration and automation at the management layer increase service agility, but the benefits of software-defined networks go beyond management.
Enterprise networks often suffer from ripple effects caused by congestion in one network element or a group of localized network elements. Services that measure their own end-to-end performance and latency avoid these ripple effects through more dynamic control of the network resources.
Greater application control also means that services can dynamically instantiate virtual private networking (VPN) flows to permit protected access to individual resources within a cloud infrastructure. Remote data replication services can occur across geographically separated data centers for disaster recovery. To support virtual machine mobility and cloud bursting, services provision underlying network connectivity and bandwidth as needed, then relinquish these resources upon completion.
To secure virtual network boundaries and protect data confidentiality, services can instantiate on-demand virtualized network security appliances such as network address translation services, firewalls and secure socket layer or VPN.
About the author:
Pankaj Shroff is a consultant at Modulus Consulting LLC. Shroff spent more than 10 years in senior leadership roles in the communications and media industry, where he led technology strategy in areas of data networking, mobile and wireless communications, machine-to-machine, converged service delivery platforms, Internet-scale Voice over IP and video delivery and data-driven addressable advertising. Reach him at firstname.lastname@example.org, visit his blog, or follow @chompi on Twitter.